Mobile robots are perhaps the most representative and, why not, most spectacular category of mechatronic systems, some of them being able to perform very life-like tasks, can handle very difficult terrain, thanks to revolutionary solutions integrated into their chassis, while some of them can even save human lives.
There are countless wheeled and tracked mobile robot building kits and platforms out there nowadays. From educational kits aimed at beginners, that are focused on demonstrating one or more principles of various nature, to full-featured platforms by means of which advanced robots can be developed. These kits come in all shapes and sizes, from very tiny micro robots, that can be operated indoors or in controlled environments, to much larger platforms, with extended features that can be operated in harsh environments and can accomplish numerous tasks. Of course, based on the degree of interactivity, we can find robots that can be remote controlled, either by dedicated consoles or even by your personal mobile device, robots activated by various stimuli and even fully autonomous robots that can continuously optimize their behavior by learning and making decisions in order to accomplish their tasks.
Applications for these robots can be practically endless, you can build your own team of wheeled football playing robots, that can be controlled by a central computer or array of processing units based on information received by video cameras and, if you have the time, the money and maybe some friends to help, you might consider building your own AGV, complete with GPS navigation, laser or sonar guidance, video analysis and whatnot.
There is also the cost of such a robotic platform, as added complexity comes at a price, from a certain level up all of these costs must be highly justified to the purpose served, development timescale must be considered as well as programming and setting up effort for a particular robot. As we mentioned in an article about one of our projects, the simple differential wheeled mobile robot, in this article we will try to shed some light on the wheeled robotic platforms market, in terms of what you should expect to get at a certain cost, key features and reviewing some popular, versatile and interesting examples of different platform types.
Budget and intermediate mobile robot kits
This is perhaps the most active part of the market, as it is targeted to a wide range of consumers, from beginners to hobbyists or even more advanced developers that want to create complex systems without exponentially increasing their costs. There are large online communities that can provide support, parts and accessories being readily available.
In this area prices can range from a few tenths of dollars to several hundreds of dollars, but a more relevant factor can be assembly and programming complexity. While also aimed at beginners and hobbyists, many robot kits found here may require some programming and electronics knowledge as well as soldering abilities.
Pololu 3pi Robot kit
A very cost-effective mobile robot building kit is the 3pi robot kit from Pololu, featuring an ATmega168 microcontroller running at 20 MHz that can be programmed using C/C++ language. Energized by its two electrical micromotors it is capable of speeds up to 1 m/s or 3,3 km/h. It is equipped with a 8×2 character monochrome LCD display, buttons and reflectance sensors.
Software-wise, tools such as Atmel’s AVR Studio or the very well-known GNU C/C++ compiler provide a very comfortable development environment. Vast online resources are available and the kit is also compatible with the Arduino development platform. Its price tag is just shy of 100 US dollars.
Lego Mindstorms NXT 2.0
With a price tag of around 300 US dollars, the Mindstorms NXT 2.0 is one of our favourite development platforms. In true Lego style, various robot types can be build from the same kit, including wheeled robots. The NXT brick is the core of the platform, holding a 32-bit microprocessor, 4 input ports and 3 output ports, a dot matrix display, Bluetooth and USB connectivity.
The programming environment interface, available for both Windows and Mac, is very easy to use and intuitive yet versatile. Blocks of various types and actions can be added and customization of parameters is one click away in most cases.
Together with the building elements, in the kit you will find 3 servomotors, 1 ultrasonic sensor, 2 touch sensors and a color identification sensor. Extensive building and programming documentation is also provided.
Numerous sensor types are available at costs of several tenths of dollars, like accelerometers, short and medium range IR sensors, barometric and even GPS sensors. Multiplexing interfaces for motors and other output devices are available. An interface for using NXT sensors and actuators with Arduino is also available.
Parallax BOE-Bot robot kit
Another one of our favourites, the BOE-Bot robot kit comes at a price of around 160 US dollars. Based on the BASIC Stamp 2 module from Parallax, it is a very versatile and cost-effective robot. By means of a breadboard, electronic circuits necessary for sensors can be easily developed and connected.
The robot chassis is made from brushed aluminium and servomotors, wheels, electronic components, wires and other necessary parts are also included.
The BS2 microcontroller module holds a 20 MHz processor and can execute around 4.000 PBASIC instructions per second. It comes with 32 Bytes of RAM, a 2 KB EEPROM which translates into around 500 PBASIC instructions, 16 I/O pins and has even a 5 VDC voltage regulator mounted on the module. Since revision J this module has been industrial-rated, expanding its versatility even further.
It can be programmed using the PBASIC 2.5 language and the programming environment includes USB communication and debugging features, as well as code highlighting for easy reading and troubleshooting. Documentation for building and programming is included and extensive online resources are available.
There are also Arduino-compatible versions of this robotic kit, with or without the Arduino module included, at prices between 110 to 150 US dollars.
Like the BS2 version, these kits also include all required hardware for building the robot and you can just plug in the Arduino module onto the mainboard. Documentation on programming the Arduino module to control the robot is included.
Inex POP-Bot mobile robot kit
The POP-Bot robot kit from Inex is fully compatible with the Arduino-mini development platform. It’s POP-168 module holds a 16 MHz ATmega168 microcontroller with a 10-bit ADC converter, 16 KB flash program memory, 512 Byte EEPROM, 1 KB RAM. Its price tag is around 150 US dollars.
It comes with an ISP programming port for the PX-400/PX-4000 device and an RS232 interface. It has 16 I/O pins, very similar in layout to the BASIC Stamp module from Parallax, 5 ports that can support analog inputs or digital I/O and 2 dedicated analog input ports, and an I2C bus port. Servomotors, wheels and sensors are included to complete the kit. A wide range of sensors is available, at costs starting at a few dollars and additional sensors can be custom made using basic electronic components.
VEX Classroom Lab kit
Another very interesting platform comes from VEX in the form of the Classroom Lab kit and is based on the powerful Cortex-M3 microcontroller. Communication takes place wirelessly through the VEXnet 802.11 link, any task can be performed this way, from controlling, downloading or debugging the robot. It comes with 8 3-wire motor ports and 2 2-wire motor ports. It has an I2C sensor port and UART fast serial ports for connecting the LCD display from VEX.
It comes with 8 high-resolution analog inputs, 12 digital I/O, Rx1 and Rx2 for connecting 75 MHz Rx/Tx crystals and 7,2 VDC battery ports. Also available there is a 9 VDC battery port for backup.
Programming is done in the easyC (various versions) or ROBOTC languages, you can choose which software package to include with the kit or buy them separately. The kit includes everything necessary to build a robot and optional accesories come in the form of expansion kits for mobility like mechanisms or wheels, power system kits, structure or sensor packages, motor controllers or remote control, as well as stand-alone motors and sensors. It can be bought at a price aroung 700 US dollars.
The Arduino platform
While not exactly a kit, the Arduino open-source development platform is extremely versatile, aiming at developers of all levels of expertise. The Arduino modules are based on various types of Atmel microcontrollers and can be programmed using the Arduino software environment. A wide range of wired or wireless communication interfaces is supported, natively or by means of add-on modules called shields. Arduino modules come in about 12 flavours, from the very small-sized Arduino Nano, to the more higher spec Arduino Pro.
Countless types of sensors are available, hardware designed for other platforms can also be controlled by means of various interfaces. Prices do not exceed a few tenths of dollars per module. Online resources and support can be easily accessed and are very extensive.
Advanced mobile robot kits
These platforms are aimed at the more experienced developers, some of them being capable of performing in industrial environments. The platforms have powerful processors, have extended mobility, sensorial and communication features, some of them even running their own operating systems. They are robust, designed to cope with very diverse environments. Prices usually range from several hundreds to several thousands of dollars.
Parallax Eddie robot platform
The Eddie robot platform is designed to be used together with a laptop and a Microsoft Kinect sensor. The laptop serves as the main control unit of the robot, while the Kinect sensor handles most of the robot’s sensing. The platform is energized by two 12 VDC electric motors, each actuating a single wheel and it also has IR and ultrasonic distance sensors to prevent blind spots not covered by the Kinect sensor.
The only connection between the platform and the laptop is over the USB interface. The platform controller is the Parallax’s own Propeller P8X32A microcontroller, that has 8 32-bit cores. It comes with an 8-channel 10-bit ADC and numerous I/O ports. Power comes from two 12V, 14,4 Ah gel-cell batteries, to provide up to 7 hours of activity, a charger being included with the kit.
The robot is fully compatible with MRDS 4 and can use sensor fusion to integrate data from the Kinect and platform sensors. It is fully customizable in terms of hardware, countless sensors and accessories being available, not to mention custom add-ons. Its price tag is around 1.200 US dollars.
RoPro Design Calliope iRobot Create netbook development platform
Being a Tekkotsu-based robot, developed at Carnegie Mellon University, the Calliope iRobot kit is essentially an Asus Eee PC 1000-series netbook mounted on an iRobot Create 4400 platform. The robot is designed for developing applications in the fields of visual processing, real-time motion control, forward and inverse kinematics, remote monitoring, teleoperation and localisation. It is available at a price of approximately 1.000 US dollars.
The laptop comes with Ubuntu Linux and with the Tekkotsu software suite preinstalled. The Tekkotsu is a free open-source project that was initially developed for the Sony Aibo, but it is now running on a variety of robots. Written in industry-standard C++ it also makes use of third party libraries like NEWMAT, libjpeg, libpng, libxml2 or zlib and uses additional packages like the CMVision, developed by Jim Bruce, and the Aibo CMPack walk engine developed by Manuela Veloso. Resources are readily available and the documentation is packed with programming examples, an extensive set of commands for various talks being readily available. Communication between the laptop and the platform is done by means of an USB-to-Create cable, a 3 Ah NiMH battery and a charger are also supplied.
RoPro Design Groma iRobot Create mapping robot
Inspired by ancient roman surveyors, the Groma iRobot Create mapping indoor robot can map the environment it operates in. It is a stand-alone iRobot Create platform that can be remotely controlled by a computer through the Bluetooth interface and its software, the “Command Center”, allows for easy interaction with the robot. Designed primarily for educational or entertaining purposes in can also be used as a capable tool for mapping certain areas and precisely executing certain programs in a known environment.
Maps, rendered in 2D coordinates, are generated on the computer and information can be assigned to different locations on them. Robot programs can be designed with the aid of its “Mission Control” programming tool and the robot can also be controlled in real time. It can be powered by 12 AA batteries or the proprietary iRobot NiMh battery. It also comes equipped with a cargo bay designed for transporting good. The price for this robot is of about 300 dollars.
Nexus Robot 4WD Mecanum robot
Based on Arduino control hardware, namely the Arduino 328 microcontroller, the 4WD Mecanum robot is a 4-wheel drive, Mecanum or Swedish wheel platform. The name of this wheel type comes from the Swedish company that developed it, Mecanum AB, back in 1973, but we will talk more about wheeled platforms and wheel types in another article.
Thanks to its wheel type this platform can move in any direction, forward, backward, sideways or turn and can do these moves by varying the speed and rotation direction of each wheel. At around 4 kilograms it is a sturdy platform, made of aluminium alloy and is also equipped with a pivoting suspension mechanism to ensure good surface contact of each wheel.
Wheels are powered by four 12 VDC motors with encoders, it comes equipped with 4 ultrasonic sensors, 4 IR sensors and an Arduino I/O expansion board. A NiMh battery and a charger are included. At 1.500 US dollars it is not cheap but it is very versatile and customizable.
POB Technology POB-Bot Hunter
The POB-Bot Hunter can be a very entertaining an customizable robot kit. It is based on an open architecture, thus making it very customizable. It is essentially a tracked platform that comes with three modules, interconnected by the POB-Bus. The POB-Eye module is a color camera module, which also holds the CPU of the robot, 15 I/O ports are available, there are also a 128 KB of flash memory and a 64 KB RAM module. The size of a stored camera image is 32 KB.
The POB-Proto module, based on a PIC microcontroller, adds I/O features to the system, motors, sensors and all additional hardware is connected to this board. An I2C bus is also available. The POB-LCD128 is a dot-matrix LCD display that can be used to develop very interesting user interfaces or monitor the activity of the robot. Communication can be done over a serial interface and an USB adapter is also included. Other items that come with the kit are 3 Sharp IR distance sensors, tracks and motors and all necessary mounting hardware. A dart gun is also include to enable hunting abilities.
Software-wise it comes very-well equipped, with graphical programming as well as scripting tools. The robot can be programmed using C, Java or Basic languages or can be graphically programmed using RISBEE, developed by POB. The software suite includes all the necessary tools for rapid development, a compiler, a loader – for uploading scripts to the robot, a bitmap editor – for easy editing of images displayed on the LCD, a pattern generator and a terminal tool for debugging purposes. The kit is priced at around 600 US dollars.
Professional mobile robotic platforms
These platforms are aimed at the professional consumer searching for advanced tools capable of accomplishing certain objectives. Generally these platforms have very powerful processing units, run operating systems and have high performance features in every aspect. They are extremely solid, depending on the application, and are designed to operate in extreme environments. They also have capable sensors like PTZ cameras or GPS modules and have high payloads. It is not uncommon for these platforms to be built to order only, as price tags range from several thousands to tenths of thousands of dollars or more.
Robotnik Guardian all-terrain high mobility research/surveillance platform
The Guardian platform from Robotnik is an extremely versatile, high-mobility robotic platform usable in almost any environment. It is equipped with a hybrid wheel and track rolling system and it can climb slopes up to 45 degrees. Its enclosure is rated at IP54, but optional weatherproofing up to IP66 can be implemented. It can be used in countless applications, from navigation or more advanced swarming scientific applications to the disposal of explosive devices and even military applications. It can also operated remotely and optional components like robotic arms can be installed.
It supports any type of sensor, like PTZ, 3D, IP and IR cameras, microphones, GPS modules and countless others. In its basic version the platform is only radio controlled but the advanced version comes with an embedded PC running Linux Real Time OS with WiFi, USB and RS232 interfaces. It even has room to house a secondary computer for increased processing power required by advanced applications such as DGPS or laser ranging.
The platform has a weight of 85 kg and supports a payload of up to 50 kg. It has two 1000 Watt traction motors and it comes with dual 12 V, 50 Ah batteries. It is built to order, according to customer specifications. It has a price tag of approximately 25.000 US dollars, but price may vary according to its configuration.
CoroWare Explorer EX-D robot development platform
The CoroWare Explorer platform is essentially a computer on wheels. The 13 kg platform is extremely sturdy, intended for outdoor operation in rough terrain. Wheels on each side are mounted on bogies that pivot about a central axle and turning is accomplished by means of skid-steering.
As a very interesting feature, in this version the computer comes with Windows XP as well as Linux preinstalled in a dual-boot configuration and a teleoperation software package is also preinstalled, while MRDS services are provided for all hardware components. The computer has a 2 GHz CPU, an 80 GB hard-disk and a 2 Megapixel color camera is also included. A battery charger is provided and AC supply tethered operation is also possible. Price is of about 13.000 US dollars.
Dr. Robot Sentinel3 WiFi mobile development platform
The Dr. Robot Sentinel3 is a fully equipped autonomous mobile robot platform. It can navigate continuously, can recharge itself, can be teleoperated and can remotely monitor certain areas. It weights 6 kg, has a sturdy aluminium chassis and can carry up to 15 kg. The platform is actuated by twin 12 VDC motors with integrated optical encoders. The robot can connect to a standard 802.11 b/g WiFi network and extended range antennas as well as 802.11a/n support are available as an option. An RS232 interface is also available.
Rapid application development can be done in the MRDS environment or with the aid of OS independent development tools, although limited in complexity when using the latter. A long list of sensors provided with the kit, such as a PTZ camera with a 704×480 resolution, 10x optical zoom and full-duplex audio, an indoor GPS sensor – this sensor is vision based, establishing up to 40 landmarks in the environment, 3 ultrasonic sensors, 2 pyroelectric (PIR) sensors for human motion detection and 7 Sharp IR distance sensors.
It has a twin 12 V 3,8 Ah NiMH battery pack, I/O module, motor driver module with position and current feedback and a small color LCD display. Also provided are a wall-mounted charger, a joystick for teleoperation purposes, cables and even a wireless router. Teleoperation and monitoring software is also provided. You get all of these at a price tag just shy of 12.000 US dollars.
Dr. Robot Jaguar tracked mobile platform
Another interesting product from Dr. Robot is the Jaguar mobile platform. Designed for extreme terrains, it has a very high mobility thanks to its tracked rolling chassis with two 360 degree articulated arms, synchronized or independent, depending on customer specification. The traction system is actuated by three 24 VDC motors, it can climb slopes up to 45 degrees, can also negotiate stairs and has a top speed of 7 km/h.
The robot can connect to any 802.11G/N WiFi network and can navigate autonomously, both indoor and outdoor, by means of GPS and 9 DOF inertial measurement unit (IMU) modules. It has a weather resistant enclosure and an extremely sturdy chassis and has a weight of about 22 kg. An integrated 640×480 resolution color camera is available and it can be equipped with an optional laser scanner. Indoor GPS, or vision based landmark sensor module can also be provided as an option. The platform comes equipped with a PWM position and speed control module for the motors.
Ready to use control and navigation software is available and a software kit – complete with SDK’s, data protocols, sample code and support for MRDS, MS Visual Studio, LabView, Matlab and Java – is included. A GamePad controller for teleoperation purposes is also provided and the robot has RS232 and Ethernet ports. A long range antenna can be supplied optionally. It is energized by a 22.2 V 10 Ah LiPo battery. This kit is available for a little over 11.000 US dollars.
InspectorBots Mega Bot wireless 4WD robot platform
A more affordable, yet sturdy and customizable platform is available from InspectorBots, in the form of the MegaBot 4WD robotic platform. It can operated indoor as well as outdoor and can be fitted with a wide range of auxiliary equipment. This is a heavy-duty platform, equipped with hi-torque electric motors that provide a 900 kg towing capacity and can even carry a human. It can be used for entertainment purposes as well in rescue or security applications. The platform has a weight of about 80 kg and can tackle slopes up to 30 degrees. The chassis is made of steel and is water resistant.
It is a modular platform so that any hardware can be installed onto it, according to the requirements and applications. It has a price tag of around 7.000 US dollars.